1221557 has 2 divisors, whose sum is σ = 1221558. Its totient is φ = 1221556.

The previous prime is 1221551. The next prime is 1221559. The reversal of 1221557 is 7551221.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 844561 + 376996 = 919^2 + 614^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221557 - 2⁴ = 1221541 is a prime.

Together with 1221559, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610778 + 610779.

It is an arithmetic number, because the mean of its divisors is an integer number (610779).

2^1221557 is an apocalyptic number.

It is an amenable number.

1221557 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221557 is an equidigital number, since it uses as much as digits as its factorization.

1221557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 700, while the sum is 23.

The square root of 1221557 is about 1105.2406977668. The cubic root of 1221557 is about 106.8984099968.

Adding to 1221557 its reverse (7551221), we get a palindrome (8772778).

The spelling of 1221557 in words is "one million, two hundred twenty-one thousand, five hundred fifty-seven".